The opportunistic fungal pathogen Aspergillus fumigatus is the causative agent of more than 90% of all Invasive Aspergillosis (IA) infections diagnosed in immunosuppressed patients. Exposure to A. fumigatus can also lead to the development of allergic asthma and Allergic Bronchopulmonary Aspergillosis (ABPA) in patients with atopic asthma or Cystic Fibrosis. Fungus-specific CD4 T cell responses are important in defense against invasive disease and mediate the development of allergic responses. Thus, understanding the factors that control the expansion and formation of fungus-specific memory CD4 T cells will lay the foundation for the future development of novel immune-based therapeutic strategies to enhance or inhibit fungus-specific immunity. In this proposal, the applicant will examine the contributions of regulatory T cells (Tregs) and T cell-intrinsic inhibitry receptors (PD-1 and CTLA-4) in controlling fungus-specific CD4 T cell responses. Moreover, the proposed studies will determine the mechanism of action of inhibitory receptors and Tregs and how they impact fungus-driven allergic airway disease progression. The applicant will be supported by a comprehensive training plan to promote her career development as an independent scientist and to help her attain a PhD degree. The long-term goal of the applicant is to become a successful, well- funded, independent researcher. As a woman of Hispanic descent the applicant is committed to contributing to the future development of research programs to address health disparities and diversity in biomedical science's workforce.